THE EFFECT OF METARHIZIUM-ANISOPLIAE (DAT F-001) CONCENTRATION AND EXPOSURE TIME ON THE SURVIVAL OF THE SUBTERRANEAN PASTURE PEST, ADORYPHORUS-COULONI (COL, SCARABAEIDAE)

The virulence of the DAT F-001 isolate of Metarhizium anisopliae for A doryphorus couloni was tested by exposing final instar larvae (L3) to concentrations of 10(1) to 10(7) spores/g in a sand-peat mix for up to 112 days at 20 degrees +/- 2 degrees C. All concentrations were patho genic to L3 larvae and survival was dependent on concentration and cor related with exposure time. The time to kill 50% of the treated larvae (LT(50)) ranged from 18.9 days (10(7) spores/g) to 82.7 days (10(1) s pores/g). The effect of DAT F-001 on feeding by L3 larvae was determin ed by comparing the production and weight of frass pellets/larva/day o f untreated control larvae with larvae rolled in sporulating cultures of M. anisopliae DAT F-001 and DAT F-054 (low virulence). Exposure to, and infection by M. anisopliae DAT F-001 had minimal impact on larval feeding. L3 larvae continued to feed at the same rate as both untreat ed and DAT F-054 treated larvae virtually until they died.